neither, both are different versions of the same idea--------integrated desktop environments with filemanagers that double as browsers and all the application associations like under windows
http://www.kde.org http://www.gnome.org
if youve got a fairly robust machine KDE is probably good for beginners, gnome right behind that
KDE and GNOME are fairly big, you can get rid of either with pkgtool and save some space, if your not gonna rebuild the kernel you can get rid of the kernel source too, just leave the rest of the kernel entries alone, you need those
kernel source is 175mb
KDE about 300mb roughly
gnome about 250mb